Not one but two of the machines that will build the North West Rail Link tunnels will be in the ground by the end of this year, Transport Minister Gladys Berejiklian announced on Tuesday. ISABELL PETRINIC reports.

Weighing 900 tonnes and about 120 metres long, Elizabeth will start digging the first of the link's twin tunnels nine kilometres to Cherrybrook station.

Concrete rings that will line these tunnels will be made in a precast concrete facility at Bella Vista.

Picture each of these rings as massive concrete wedding rings about seven metres wide, locked together one after the other to form the inside of the tunnels. About 16,500 rings will be made.

As the tunnelling machine cuts about 1.7 metres of rock, a ring will be put into place while the machine continues moving forward.

The crushed rock will be removed on a conveyer belt through each TBM and back to the tunnelling work site to be re-used.

Mr Baird confirmed the Northwest Rapid Transit Consortium as the project's preferred operator. The contract will be signed next month.

The media was told all trains on the automated network would be monitored remotely from a new Rapid Transit Rail Facility at Tallawong Road, Rouse Hill, as well as by roaming attendants on the trains.

How customers would exit the trains in an emergency would be decided in consultation with the consortium.

Mr Baird said the government would set and control the fares on the North West Rail Link and the operator would be fined if contract requirements, such as running trains on time and making they sure they were clean, were not met.